Safety device for toggle latch



July 5, 1966 F. WHEELER SAFETY DEVICE FOR TOGGLE LATCH Filed Deo. 17, 1963 INVENTOR. Fb@ NK WH EEL EQ Elma/MX @Comm QTTOPNEYS United States Patent O 3,259,412 SAFETY DEVICE FOR TOGGLE LATCH Frank Wheeler, Little Falls, NJ., assignor to Camloc Fastener Corporation, Paramus, NJ., a corporation of New York Filed Dec. 17, 1963, Ser. No. 331,254 2 Claims. (Cl. 292-113) My invention relates to a toggle latch and more particularly to a device for preventing the latch from apparently being operated when the drawhook is not-actually ,in engagement with the strike.

One class of latches of the prior art for securing a separable member to a body are blind latches which are operated while the engaging parts are out of view of the operator. Such latches are commonly employed in flushtype latches for securing separable parts to the body of an aircraft or the like where air drag is to be minimized.

One particular type of blind latch is a toggle latch in which a handle pivotally supported on one of the members carries a drawhook adapted to be moved into engagement with a strike on the other of the two members as the handle is moved into an opening in the part carrying the handle. Owing to the fact that the hook and strike are not visible to the operator when the latch is operated, `it may occur that the handle is moved to its home position when the drawhook is not actually in engagement with the strike so that the latch apparently is functioning whereas actually it is inoperative. The danger of this condition is readily apparent not only in the case of aircraft but in any installation in which parts thought to be secured are not actually being held together with suicient force, if at all.

I have invented a safety device for a toggle latch which overcomes the problem outlined hereinabove. My safety device prevents the latch from apparently having been operated when in fact it is in an inoperative condition. My device prevents the latch handle from being moved to its home position unless the drawhook is actually in engagement with its strike. My device is simple in construction for the result achieved thereby. It is inexpensive to manufacture. Moreover, it may be applied to eX- isting toggle latches.

One object of my linvention is to provide a safety device for a toggle latch which prevents the latch from apparently having been operated though it is in an inoperative condition.

Another object of my invention is to provide a safety device for a toggle latch which prevents the latch handle from being moved to its home position unless the drawhook is in engagement with the strike.

A further object of my invention is to provide a safety device for a toggle latch which is simple in construction.

Still another object of my invention is to provide a safety device for a toggle latch which is inexpensive to manufacture.

Yet another object of my invention is to provide a safety device for a toggle latch which may be applied to existing toggle latches.

Other and further objects of my invention will appear from the following description.

In general my invention contemplates the provision of a safety device for a toggle latch wherein a safety lock which normally prevents movement ofthe latch handle to its home position is released in response to proper positioning of the handle-carrying drawhook for engagement "ice i with the strike to permit the handle to be moved to its home position to operate the latch.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGURE l is a side elevation of a toggle latch provided with my ysafety device with parts broken away and with other parts shown in section.

FIGURE 2 is a side elevation of a toggle latch provided with my safety device with parts broken away and with other parts shown in section illustrating the positions 0f the parts before the latch is operated.

FIGURE 3 is a plan View of a toggle latch provided with my safety device taken along the line 3--3 of FIG- URE 1.

Referring now to the drawings, a latch assembly indicated generally by the reference character 10 provided with my safety device is adapted to join a first member 12 in assembled relationship with a member 14. Member 14 carries a strike such as a U-shaped fitting 16 which is secured to the member 14 by any suitable means known to the art.

Respective brackets 26 and 28 secured to the member 12 by any suitable means such, for example, as: welding or the like carry a latch-mounting bolt 30 for supporting the latch -assembly 10.

The latch assembly 10 includes a handle 32 provided with side flanges 34 and 36 which support a mounting bolt spacer 38 supported on the bolt 30 when the latch assembly 10 is mounted on the member 12. In this manner, the handle 32 is mounted on the member 12 for pivotal movement between a position such as is shown in FIGURE 2 where the handle is out of an opening 40 in the member 12 and a position shown in FIGURES 1 and 3 at which the handle 32 is disposed in the opening 40 so as to be flush with the surface of member 12.

A pin 42 carried by the flanges 34 and 36 of the handle 32 supports bifurcations 44 and 46 at one end of the drawhook 48 pivotally to mount the drawhook on the handle. The drawhook 48 is adapted to engage the member 16 in the operative position of the latch assembly 10 in a manner to be described. Spring 50 surrounding the pin 42 bears with one end 52 on the underside of handle 32 and with the other end 54 on a pin 56 carried by the bifurcation 44. Thus, spring 50 normally urges the drawhook 48 and the handle 32 away vfrom each other.

I provide the toggle latch assembly 10 with a catch 58 pivotally supported on a pin 60 carried by the flanges 34 and 36 of handle 432. A spring 62 carried by the pin 60 bears with one end 64 on the underside of the handle 32 and with its other end 66 on the underside of the catch 58. Spring 62 acts on the catch 58 normally to urge it to a position at which the catch is nested within an opening 68 in handle 32. A toe 69 on the catch 58 limits its movement in the direction in which it is urged to move by the spring 62.

Catch 58 is provided with a recess 70 adapted to engage a pin 72 on drawhook 48 when the latch assembly 10 is in its operative position to lock the assembly against accidental release. When, in a manner to be described, the latch is to be released, catch 58 is actuated to move it in a clockwise direction as viewed in FIGURE 1 against the -action of spring 62 to move the recess 70 away from pin 72 to release the latch.

From the structure thus far described, it will readily be apparent that the operator of the latch assembly is unable to view the drawhook 48 and the member 16 as he moves the handle 32 to its home position in the opening 40. Owing to this fact, it may happen in assemblies of the prior art that the latch 32 is moved into its home position although the drawhook 48 is not yet in engagement with the member 16. Thus, the members 12 and 14 are thought to `be secured though in fact the` latch assembly 10 is inoperative.

I provide the latch assembly 10 with safety stop plates 74 separated by -a spacer 86 secured to the plates by rivets 84. The pin 72 pivotally supports plates 74 and spacer 86. Plates 74 support a pin 76 and are provided with surfaces 78 which in one position of the stop are in the path of movement of the spring 62 carried Aby the pin 60 as the handle 32 moves to its closed position. I provide the plates 74 with arms 80 adapted to close the opening 82 of the drawhook 48 in the position of the stop plates 74 at which surfaces 78 are in the path of movement of the pin 60.

A spring 83 carried by the pin 76 bears with one end 90 against the spacer 86 and with its other end 92 on the drawhook 48. Thus, spring 88 normally urges the stop plates 74 to rotate in a clockwise direction as viewed in FIGURES l and 2. When the stop plates 74 are free, spring 88 -moves them in a clockwise direction until a surface 96 on the spacer 86 engages the upper surface of the drawhook 48 as viewed in FIGURE 2. This is the position of the stop plates 74 referred to hereinabove at which the surfaces 78 are in the path of movement of the spring 62 carried by the pin 60 as the handle is; moved into the opening 40. At the same time the arms 80 block the opening 82 of the drawhook 48. If now the drawhook 43 is properly positioned so that the fitting 16 can move into the opening 82, movement of the handle 32 toward the opening 4t) causes the tting 16 to rotate the stop plates 74 in a counterclockwise direction. Initially, this movement forces the arms 80 out of the position at which they block the recess 82. Upon continued movement of the handle, pin 60 rides along the upper surfaces of stop plates 74 until the parts reach the position sho-wn in FIGURE 1 at which the slot 70 has moved over the pin 72 to lock the latch against accidental release.

In operation of my safety device for toggle latches with the members 12 and 14 out of engagement, they are brought together With litting 16 of member 14 passing through opening 18 and slot 20 to a position at `which it is thought to be 'able to move into recess 82. Before operation, the parts of latch assembly 10 are in the positions shown in FIGURE 2 at which the surfaces 78 are in the path of spring 62 on pin 60 and arms 8) block recess 82. Then the handle 32 is moved down toward the opening 40. If for some reason the parts have not been properly positioned so that for example, the end of the drawhook hits the fitting 16, the handle cannot be moved completely into the opening 40. However, if the parts are initially in the proper position or if they are adjusted tto the proper position so that the tting 16 engages the arms 80, then as handle 32 is moved into the opening 4@ the iitting 16 moves the stop plates 74 in a counterclockwise direction as viewed in the drawings to expose the opening 82. Upon continued movement of the handle 32 toward the opening 48, spring 62 carried by pin 60 cams stop plates 74 to the position shown in FIGURE 1 and recess 82 engages the fitting 16 to draw the members 12 and 14 together by virtue of the toggle action of the latch. Ultimately, catch S8 rides over the pin 72 until the .pin drops into the opening 70 thus to lock the parts in the operated position.

When it is desired to release the latch, catch 58 is manually rotated in a clockwise direction to move the slot 7@ away from pin 72. VWhen this has been done, spring Sil causes the handle 32 to pop out of the opening 40 to a position at which it is accessible to permit the latch to be released by moving recess 82 away from fitting 16. In the course` of this movement spring 88 returns the stop plates 74 to the position shown in FIGURE 2 at which it prevents the assembly from being operated unless the drawhook and the tting 16 are in the proper relative position for correct operation.

It will be seen that I have accomplished the objects of my invention. I have provided a safety device for a toggle latch which prevents the latch handle from being moved to its home position unless the drawhook and its strike are in `the correct relative position for proper operation. My device prevents -a latch from being apparently operated when in fact it is inoperative. It is simple in construction and is inexpensive to manufacture. It may be applied to already existing latches.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other Vfeatures and subcombinations'. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims witho-ut departing from the spirit of my invention. It is, therefore, to be understood `that my invention is not to be limited to the specific details shown and described.

Having thus described my invention what I claim is:

1. A latch assembly `for securing a tirst lbody to a second body having an engageable element thereon including in combination a handle and a catch means pivoted thereon, means mounting said handle on said i'irst body for movement between a release position and a home position, a drawhook having an element engaging portion, means mounting said drawhook on said handle for movement in response .to movement of said handle between a lirst position out of engagement with said element and a second position in engagement with said element, said catch means adapted to engage said drawhook and adapted to retain said handle in said home position ya bell crank having a pair of arms, interengageable means on one of said arms and on said handle adapted to prevent movement of said handle into its home position, means mounting said bell crank on said drawhook at the point of engagement of said catch means with said drawhook, limit means for constraining said bell crank for movement between a first position at which said interengageable means are adapted to engage and said other arm blocks said dnawhook portion; and a second position at which said interengageahle means are out of engagement and said arm is clear of said portion, and means biasing said bell crank t-o said rst position, said limit means including a Iboss on said bell crank for limiting the movement of said bell crank under the action of said resilient means.

2. A latch assembly for securing a lirst body to a second body having an engageable element thereon including in combination a handle and catch means pivoted thereon, means mounting said .handle on said first body for movement between a release position and a home position, a drawhook having an element-engaging portion,

means responsive to actuation of said handle for moving the drawhook between a irst position out of engagement with said element and a second position in engagement with said element, said catch means adapted to engage said drawhook and adapted to retain said handle in said home position, a stop comprising a pair of cranks, interengageable means on one of said cranks and on the pivot of said -catch lmeans of said handle adapted to prevent l movement of said handle into its home position, means pivotally mounting said st-op on said drawhook, limit means constraining said stop for movement between a first position at which said interengageable means are adapted to engage each other and said other crank blocks said drawhook portion and a second position at which said interengageable means is disabled and said other 5 6 crank is clear of said drawhook portion, and means bias- 3,005,065 11/ 1961 Jellies 200-61.68 ing said stop to said rst position. 3,189,375 6/ 1965 Getman 292-111 References Cited by the Examiner PATRICK A. CLIFFORD, Primary Examiner.

UNITED STATES PATENTS 5 JOSEPH D. SEERS, Examiner.

2,712,955 7/1955 Andrews 292-113 I. R, MOSES, Assistant Examiner.

2,738,211 3/1956 Schlueter 292-111 

1. A LATCH ASSEMBLY FOR SECURING A FIRST BODY TO A SECOND BODY HAVING AN ENGAGEABLE ELEMENT THEREON INCLUDING IN COMBINATION A HANDLE AND A CATCH MEANS PIVOTED THEREON, MEANS MOUNTING SAID HANDLE ON SAID FIRST BODY FOR MOVEMENT BETWEEN A RELEASE POSITION AND A HOME POSITION, A DRAWHOOK HAVING AN ELEMENT ENGAGING PORTION, MEANS MOUNTING SAID DRAWHOOK ON SAID HANDLE FOR MOVEMENT IN RESPONSE TO MOVEMENT OF SAID HANDLE BETWEEN A FIRST POSITION OUT OF ENGAGEMENT WITH SAID ELEMENT AND A SECOND POSITION IN ENGAGEMENT WITH SAID ELEMENT, SAID CATCH MEANS ADAPTED TO ENGAGE SAID DRAWHOOK AND ADAPTED TO RETAIN SAID HANDLE IN SAID HOME POSITION A BELL CRANK HAVING A PAIR OF ARMS, INTERENGAGEABLE MEANS ON ONE OF SAID ARMS AND ON SAID HANDLE ADAPTED TO PREVENT MOVEMENT OF SAID HANDLE INTO ITS HOME POSITION, MEANS MOUNTING SAID BELL CRANK ON SAID DRAWHOOK AT THE POINT FOR ENGAGEMENT OF SAID CATCH MEANS WITH SAID DRAWHOOK, LIMIT MEANS FOR CONSTRAINING SAID BELL CRANK FOR MOVEMENT BETWEEN A FIRST POSITION AT WHICH SAID INTERENGAGEMENT MEANS ARE ADAPTED TO ENGAGE AND SAID OTHER ARM BLOCKS SAID DRAWHOOK PORTION; AND A SECOND POSITION AT WHICH SAID INTERENGAGEABLE MEANS ARE OUT OF ENGAGEMENT AND SAID ARM IS CLEAR OF SAID PORTION, AND MEANS BIASING SAID BELL CRANK TO SAID FIRST POSITION, SAID LIMIT MEANS INCLUDING A BOSS ON SAID BELL CRANK FOR LIMITING THE MOVEMENT OF SAID BELL CRANK UNDER THE ACTION OF SAID RESILIENT MEANS. 